1. Field of the Invention
The present invention relates to radio navigation generally, and more specifically, to localizer or glide-slope signal generating arrangements for the instrument-landing system of the known type.
2. Description of the Prior Art
ILS equipment has been extensively described in the prior technical literature, including the patent literature. A localizer or glide-slope facility typical of this art is described in a book by E. Kramar, "Funksysteme fur Ortung and Navigation", Verlag Berliner Union GmbH, Stuttgart 1973, on pages 193 to 205, and shown in FIG. 1, included with this description. In the aforementioned reference, it is stated that a localizer or a glide-slope facility which radiates the course and clearance signals at different frequencies requires two complete transmitters. This concept is generally accepted in the prior art.
Quite obviously, the cost of these two separate transmitters is a factor militating against the reduction of ILS system cost which has been considered important in making this instrumentation widely available for small airports.
The manner in which the present invention affords a significant reduction in cost and complexity for these systems will be understood as this description proceeds.
In accordance with the foregoing prior art description, it may be said to be the general object of the invention to reduce the amount of equipment required for ILS localizers and/or glide-slope ground facilities which radiate course and clearance signals at different frequencies.